Scientific Investigations
· Variables are the different factors that can change in an experiment – there are 3 types of variables:
o Independent variable – the variable that we change or plan to change before we start the experiment.
o Dependent variable – the variable that we measure, or that is changed by the experiment
o Constant – variables that do not change or that we keep the same through the entire experiment.
· Controls are the standard experimental result that we are comparing all of our results to.
· Experiments should be repeated several times to be considered valid results!
Hypotheses are educated predictions or guesses about the outcome of an experiment
Experimental Errors – errors that make the experiment not valid or affect outcomes.
Scientific Theories – an explanation or model backed by results obtained from many tests or experiments
Scientific Law – a rule that describes the behavior of something in nature
Density
· Mass/Volume
· May have to use water displacement to determine volume of an irregularly shaped substance
Maps and Landforms
· Landforms
o Plains – large flat areas – ex. Great Plains and Coastal Plain of Virginia
o Plateaus – raised areas that are flat on top – uplifted by earth forces – ex. Colorado Plateau, and Cumberland Plateau of Virginia
o Folded Mountains – created by forces pushing in from the sides. – ex. Rocky Mountains, and the Appalachian Mountains of Virginia (much older than the Rockies)
o Upwarped Mountains – created by lifting forces deep under the earth. Often the tops of the ridges erode into peaks – ex. Adirondack Mountains of NY and Black Hills of SD
o Fault Block Mountains – created by faults as they move in opposite directions. Ex. Grand Tetons in Wyoming and the Sierra Nevadas in California
o Volcanic Mountains – formed from volcanic activity in the earth.—ex. Mount St. Helens in Washington.
· Latitude/Longitude
o Latitude lines
§ Parallel to each other horizontally around the earth
§ Their measurements will be from 0° to 90°North of the equator, and 0° to 90° South of the equator.
§ 0° Latitude is the Equator
§ 90° N is the North Pole
§ 90° S is the South Pole
§ From the North Pole to the South Pole there are a total of 180° of Latitude
o Longitude lines
§ Run vertically up and down, and meet at the Poles.
§ Their measurements will be from 0° to 180° East of the Prime Meridian and 0° to 180° West of the Prime Meridian.
§ 0° Longitude is the Prime Meridian
§ 180° Longitude is the International Date Line (IDL)
· Travel west across the IDL, you move your calendar forward one day
· Travel east across the IDL, you move your calendar backward one day
§ There are a total of 360° of Longitude
o Both Longitude and Latitude lines can be further broken down into Minutes and Seconds as measurement units. There are 60 “minutes” between 2 consecutive Longitude lines.
POINT / LOCATIONA / lat. 5° 59' 45" N; long. 71° 00' 45" W
B / lat. 5° 59' 09" N; long. 71° 01' 00" W
C / lat. 5° 59' 30" N; long. 71° 00' 00" W
Topographical Maps – models the changes in elevation of the Earth.
· Contour lines – lines on the map that connect points of equal elevation
· Index contours – lines that are clearly marked with their elevation
· Contour Interval – difference in elevation between adjacent (side-by-side) contour lines
· Rules
o Contour lines close around hills and basins. Basins will usually have small marks pointing inward to indicate a depression.
o Contour lines never cross
o Contour lines that are close together indicate a steep slope. Contour lines very far apart indicate much flatter land.
o Contour lines form Vs that point upstream when they cross streams.
· Map Scale – the ratio between the distance on the map and the distance on Earth
o If no units are expressed, the ratio has the same units on both sides of the ratio
o Example 1:24,000 means 1 unit on the map equals 24,000 units on the Earth. Units may be inches, cm, mm, etc.
Minerals
Characteristics: A naturally occurring, inorganic, solid with a definite chemical composition and a crystalline structure.
Physical Properties:
Hardness:
· how easily a mineral can be scratched –
· Compared using the Moh’s Scale of Hardness
Color: easily determined, least useful property for identification
Luster: way a mineral reflects light (shines)
· Metallic – like a metal
· Nonmetallic – dull, glassy, silky, earthy, etc.
Streak:
· color of a mineral in powdered form
· Tested by rubbing the mineral against an unglazed porcelain tile called a streak plate
Cleavage:
· Breakage pattern of a mineral
· Breaks along a smooth flat surface
Fracture:
· Breakage pattern of a mineral
· Breaks with rough or jagged uneven surfaces
Specific Gravity:
· The ratio of its weight compared to an equal volume of water
· Tested in field using the heft test – which one of equal size feels heavier
Magnetism: acts like a magnet
Effervescence: fizzes with acid
Mineral Uses:
Ores – a mineral that is useful and profitable such as pyrite, magnetite, hematitie, galena, graphite, etc.
Gems – a mineral that is rare and beautiful – examples: diamonds, ruby, and sapphires
Rocks
Rock Cycle describe how one type of rock changes into another
Rocks:
· Differ From minerals
· Are a mixture of rock fragments, minerals and/or organic matter
Igneous rocks:
· Form from the cooling and crystallization of magma/lava
· Based on texture:
o Intrusive:
§ Forms inside earth from magma
§ Large mineral grains (coarse-grained texture)
§ Examples - Granite
o Extrusive:
§ Forms on or near earth’s surface
§ Small mineral grains (fine-grained texture)
§ Examples – Pumice, Obsidian, Basalt
· Based on composition:
o Granite:
§ Light colored and Less dense
§ Silica rich
§ Examples - Granite
o Basalt:
§ Dark and dense
§ Low silica content / rich in magnesium and iron
§ Examples – Basalt,
Metamorphic Rocks
· Form from heat and pressure applied to pre-existing rocks (process called metamorphism)
· Types:
o Foliated:
§ Flattened mineral grains
§ Banding and/or layering
§ Examples: Gneiss, Slate, Schist
o Nonfoliated:
§ Increased mineral grain size
§ Not layered
§ Examples: Marble and Quartzite
Sedimentary Rocks
· Formed by the compaction (pressing) or cementation (glueing) of sediments or by chemical precipitation or evaporation
· Types:
o Clastic (Detrital):
§ Made of rock / mineral fragments
§ Examples: sandstone and shale, conglomerate (rounded sediments) and breccia (angular sediments)
o Chemical:
§ Formed from precipitation within a solution or evaporation of a solution
§ Examples: Limestone
o Organic:
§ Formed from the remains of once living organisms
§ Examples: Coal, Coquina, Fossil-rich Limestone
Weathering & Soil
Weathering: the process by which rocks are broken down by action of water, air and organisms into sediments.
Sediments: are pieces of rocks and organic matter that is classified by size not composition.
Clay - Silt - Sand - Pebble - Boulder
Types of Weathering
· Mechanical –
o Breaks down rocks by physical processes without a chemical change
o Examples: rootpry, ice wedging (frost action), burrowing animals
· Chemical –
o Chemical reactions cause mineral sin rocks to dissolve or change
o Examples: natural acids, oxidation (rust), plant acids
o Main agent = water
The rate of weathering is affected by:
· Climate (chemical weathering = tropical climate)
· Rock type and composition
· Amount of precipitation
Soil – a mixture of sediment derived from weathered rock mixed with organic matter
Humus – the dark-colored decaying organic matter
Soil Profile – all the layers of soil
Horizon – each individual layer of the soil profile
Leaching – the process where dissolved minerals where carried by water from one horizon to the next
Litter – mixture of twigs, leaves and other organic matter than will eventual decay to form humus
Soil Profile
Horizon A: (topsoil) most evolved, darkest, contains litter, humus, plant roots, burrowing animals, finest sediments, plant nutrients.
Horizon B: (subsoil). Little humus, lighter color, some plant roots, minerals from leaching.
C Horizon: partially weathered rock. Bottom Layer.
Bedrock: below C-horizon
Soil Loss – humans, deforestation, poor farming practices, overgrazing and construction have all lead to soil loss
Methods to Reduce Soil Loss –
· Planting vegetation
· Crop rotation
· No-till Farming
· Contour Farming
Erosion
Erosion – The transportation of sediment by wind, water, ice or gravity
Deposition – The dropping of transported sediment in a new location
Erosion by Gravity (Mass Movements / Mass Wasting)
· Erosion down slopes usually due to heavy rain or tectonic activity
· Types:
o Slump:
§ When a mass of matter slips down leaving a curved scar behind
§ Slow process
o Creep:
§ movement of sediments due to freezing and thawing
§ Causes posts and fences on hills to lean
§ Extremely slow
o Rockslides:
§ Rocks falling down hill knocking other rocks loose along the way
§ Leaves a pile of rocks at bottom of hill
§ Fast process
o Mudflows:
§ When heavy rains turn dry soil into a thick muddy paste that moves downhill
§ Destroys anything in its path
§ Leaves cone-shaped deposit
§ Extremely fast
Glacial Erosion
Glaciers-
· a large mass of moving ice and snow
· Erodes by abrading (bulldozings) or plucking
Plucking: similar to ice wedging – boulders and large sediments are plucked from the bottom of glacier due to freezing and thawing of meltwater
Deposition of material
· Till –
o deposited by glacier itself
o Unsorted
· Outwash –
o Deposited by glacial meltwater
o Sorted by size
Wind Erosion
Deflation – the erosion of fine sediment, leaving behind the larger particles
Abrasion – sediment is blown against other rocks – Causes rocks to become pitted and polished (like sandblasting)
Deposition:
Loess – thick, light colored deposits of fine sediment
Dunes – sediments piling around an object such as a bush or large rock
Natural Resources
Energy – the ability to cause change
· Many of our resources are used to create energy
Non-Renewable
· Cannot be easily formed – may take millions of years to replace
· Fossil Fuels
· Resources created from the remains of plants and animals which were buried millions of years ago.
· The Reserve is the amount of the fuel that can be extracted from the Earth at a profit using current technology.
o Coal
§ A sedimentary rock formed from compacted and transformed plant material
§ The most abundant fossil fuel in the world
§ May be removed by strip mining or underground mining. Strip mining is very damaging to the environment.
§ One of Virginia’s most important resources
· Peat – Decayed plant material. The first step in Coal formation
· Lignite – Brown Coal. Soft, about 50% Carbon. Produces a fair amount of smoke when burned.
· Bituminous – Black Coal. Brittle. Majority of the coal burned is bituminous. Smoky and contains sulfur which is an environmental pollutant.
· Anthracite – Hard Coal. Highest amount of Carbon. Relatively clean burning compared to other coals.
o Oil
§ Thick, black liquid formed from the buried remains of microscopic marine organisms
§ A Hydrocarbon
§ May be refined and used in many different ways including heating, gasoline, lubricants and manufacturing.
o Natural Gas
§ A clear gas formed from the buried remains of microscopic marine organisms
§ A Hydrocarbon
Nuclear Energy
· Created from the splitting of atoms of heavy elements to create energy
· Nuclear waste requires safe storage for 10,000 years before it can reenter the environment
Inexhaustible Energy sources
· Solar
o Energy from the sun
o Advantage - Clean and limitless
o Disadvantage - doesn’t work on cloudy days. Solar cells are not yet very efficient.
· Wind
o Uses wind farms – large collections of wind turned turbines
o Advantage - Clean and free
o Disadvantage – requires large areas with constant wind sources. May kill or injure wildlife.
· Hydroelectric
o Dams trap water and then create electricity as the water turns turbines.
o Advantage - Relatively clean and renewable
o Disadvantage – Dams can change waterways, create erosion, and flood out wildlife
· Geothermal Energy
o Takes advantage of underground magma to heat water. Steam is then used to make electricity.
o Requires a source of water
Renewable Energy Sources
Biomass – energy obtained by burning organic material, including wood, alcohol, and garbage.
· Wood is the most widely used biomass. Burning it may create pollution, and it requires replanting of forests to be sustainable.
· Alcohol (Ethanol) can reduce oil use and is efficient, but requires a source, such as corn
· Garbage can be burned to create a lot of energy, and saves landfill space but may pollute the air.
Mineral Resources
· Ores are deposits where minerals exist in high enough concentrations to be mined at a profit.
· Refining is the extraction of a useful substance from an ore.
· Smelting is a chemical process used to remove impurities from ore. Heat may also be used. These processes require energy from some type of fuel, and may create leftover toxic materials.
· Minerals may be used for industrial uses or building materials.
Virginia’s Top Mineral
Resources include
Hydrology
Hydrological Cycle (Water Cycle)
o Evaporation – liquid water turns into a gas (water vapor)